[clang][bytecode] Add Pointer::initializeAllElements() (#151151)

To initialize all elements of a primitive array at once. This saves us
from creating the InitMap just to destroy it again after all elements
have been initialized.

Author: tbaederr

clang/lib/AST/ByteCode/Interp.h

@@ -481,13 +481,11 @@ inline bool Mulc(InterpState &S, CodePtr OpPC) {
     Floating RA = S.allocFloat(A.getSemantics());
     RA.copy(ResR);
     Result.elem<Floating>(0) = RA; // Floating(ResR);
-    Result.atIndex(0).initialize();
 
     Floating RI = S.allocFloat(A.getSemantics());
     RI.copy(ResI);
     Result.elem<Floating>(1) = RI; // Floating(ResI);
-    Result.atIndex(1).initialize();
-    Result.initialize();
+    Result.initializeAllElements();
   } else {
     // Integer element type.
     const T &LHSR = LHS.elem<T>(0);
@@ -505,7 +503,6 @@ inline bool Mulc(InterpState &S, CodePtr OpPC) {
       return false;
     if (T::sub(A, B, Bits, &Result.elem<T>(0)))
       return false;
-    Result.atIndex(0).initialize();
 
     // imag(Result) = (real(LHS) * imag(RHS)) + (imag(LHS) * real(RHS))
     if (T::mul(LHSR, RHSI, Bits, &A))
@@ -514,8 +511,8 @@ inline bool Mulc(InterpState &S, CodePtr OpPC) {
       return false;
     if (T::add(A, B, Bits, &Result.elem<T>(1)))
       return false;
-    Result.atIndex(1).initialize();
     Result.initialize();
+    Result.initializeAllElements();
   }
 
   return true;
@@ -541,14 +538,12 @@ inline bool Divc(InterpState &S, CodePtr OpPC) {
     Floating RA = S.allocFloat(A.getSemantics());
     RA.copy(ResR);
     Result.elem<Floating>(0) = RA; // Floating(ResR);
-    Result.atIndex(0).initialize();
 
     Floating RI = S.allocFloat(A.getSemantics());
     RI.copy(ResI);
     Result.elem<Floating>(1) = RI; // Floating(ResI);
-    Result.atIndex(1).initialize();
 
-    Result.initialize();
+    Result.initializeAllElements();
   } else {
     // Integer element type.
     const T &LHSR = LHS.elem<T>(0);
@@ -590,7 +585,6 @@ inline bool Divc(InterpState &S, CodePtr OpPC) {
       return false;
     if (T::div(ResultR, Den, Bits, &ResultR))
       return false;
-    Result.atIndex(0).initialize();
 
     // imag(Result) = ((imag(LHS) * real(RHS)) - (real(LHS) * imag(RHS))) / Den
     if (T::mul(LHSI, RHSR, Bits, &A) || T::mul(LHSR, RHSI, Bits, &B))
@@ -599,8 +593,7 @@ inline bool Divc(InterpState &S, CodePtr OpPC) {
       return false;
     if (T::div(ResultI, Den, Bits, &ResultI))
       return false;
-    Result.atIndex(1).initialize();
-    Result.initialize();
+    Result.initializeAllElements();
   }
 
   return true;

clang/lib/AST/ByteCode/InterpBuiltin.cpp

@@ -1099,10 +1099,8 @@ static bool interp__builtin_complex(InterpState &S, CodePtr OpPC,
   Pointer &Result = S.Stk.peek<Pointer>();
 
   Result.elem<Floating>(0) = Arg1;
-  Result.atIndex(0).initialize();
   Result.elem<Floating>(1) = Arg2;
-  Result.atIndex(1).initialize();
-  Result.initialize();
+  Result.initializeAllElements();
 
   return true;
 }
@@ -1728,9 +1726,9 @@ static bool interp__builtin_elementwise_popcount(InterpState &S, CodePtr OpPC,
         Dst.elem<T>(I) =
             T::from(Arg.elem<T>(I).toAPSInt().reverseBits().getZExtValue());
       }
-      Dst.atIndex(I).initialize();
     });
   }
+  Dst.initializeAllElements();
 
   return true;
 }
@@ -2314,12 +2312,10 @@ static bool interp__builtin_elementwise_sat(InterpState &S, CodePtr OpPC,
       llvm_unreachable("Wrong builtin ID");
     }
 
-    INT_TYPE_SWITCH_NO_BOOL(ElemT, {
-      const Pointer &E = Dst.atIndex(I);
-      E.deref<T>() = static_cast<T>(Result);
-      E.initialize();
-    });
+    INT_TYPE_SWITCH_NO_BOOL(ElemT,
+                            { Dst.elem<T>(I) = static_cast<T>(Result); });
   }
+  Dst.initializeAllElements();
 
   return true;
 }

clang/lib/AST/ByteCode/Pointer.cpp

@@ -495,6 +495,19 @@ void Pointer::initialize() const {
   getInlineDesc()->IsInitialized = true;
 }
 
+void Pointer::initializeAllElements() const {
+  assert(getFieldDesc()->isPrimitiveArray());
+  assert(isArrayRoot());
+
+  InitMapPtr &IM = getInitMap();
+  if (!IM) {
+    IM = std::make_pair(true, nullptr);
+  } else {
+    IM->first = true;
+    IM->second.reset();
+  }
+}
+
 void Pointer::activate() const {
   // Field has its bit in an inline descriptor.
   assert(PointeeStorage.BS.Base != 0 &&

clang/lib/AST/ByteCode/Pointer.h

@@ -725,6 +725,10 @@ class Pointer {
 
   /// Initializes a field.
   void initialize() const;
+  /// Initialize all elements of a primitive array at once. This can be
+  /// used in situations where we *know* we have initialized *all* elements
+  /// of a primtive array.
+  void initializeAllElements() const;
   /// Activats a field.
   void activate() const;
   /// Deactivates an entire strurcutre.